Doom 3 was fairly underwhelming. Aside from the excessive lack of lighting, the enemy encounters grew terribly formulaic. You enter a room, a demon spawns behind you, you kill him, then another demon spawns behind you again. Rinse and repeat for the whole game.

Dead Space handled enemy spawning in a much less predictable way. Enemies would always appear out of grates, shafts, etc, but the level designers put grates and shafts everywhere, even in areas without any enemy encounters. You never knew when an enemy would pop out, so you were always extra cautious around them.